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As we pack more and more into our busy schedules, something’s gotta give. More often than not, that something is sleep.

The U.S. Centers for Disease Control and Prevention estimates that 50 to 70 million Americans are chronically sleep-deprived. The reasons are just what you would expect — too many responsibilities at work, at home, excessive TV watching, and Web surfing. But there are two other culprits that may be to blame: caffeine and nicotine.

Cruising All Day With Caffeine

With a coffee shop seemingly on every street corner, it’s tempting to turn to coffee to stay alert. In fact, according to the National Sleep Foundation, caffeine has been called the most popular drug in the world. And it’s not just in coffee. Caffeine can be found in everything from tea and chocolate to certain soft drinks and medications.

One reason it’s so popular is because, when we’re feeling sleepy, caffeine can temporarily increase alertness by pumping up adrenaline production and interfering with sleep-inducing chemicals. Not only that, it’s fast. It can be absorbed quickly — within 15 minutes — as it gets into the bloodstream through the stomach and small intestine.

Is Caffeine Keeping You Up?

But the news is not all good. “Caffeine is a stimulant and therefore impedes sleep,” says David C. Brodner, MD, medical director of the Center for Sleep, Allergy, and Sinus Wellness in Boynton Beach, Fla.

It stays in the body for a relatively long period of time, taking six hours for just one half of the caffeine to be eliminated. Too much caffeine may cause insomnia, which can manifest itself as trouble falling asleep or staying asleep. A “normal” amount of caffeine consumption is about 250 milligrams per day, or the equivalent of three eight-ounce cups of coffee. Consumption becomes excessive at 500 mg a day, or six or more eight-ounce cups of coffee. Excessive caffeine can cause frequent urination — and multiple trips to the bathroom during the night.

Ironically, not only can too much caffeine cause sleep problems, but so can cutting down on caffeine intake — this can temporarily result in sleep issues while the body goes through withdrawal.

Nicotine is also a stimulant, and nicotine side effects can cause insomnia and withdrawal symptoms similar to caffeine. Smoking may also create other sleep disturbances. Research has shown that smokers spend more time sleeping lightly and less time in deep sleep than non-smokers. The biggest differences are found early in the night’s sleep, corresponding to the time when the highest levels of nicotine are present in a smoker’s blood. Scientists also speculate smokers may have withdrawal symptoms closer to morning, and that could contribute to sleep problems as well.

There’s no doubt caffeine and nicotine can cause insomnia and interfere with restorative sleep. Try cutting back on your consumption and you might find yourself sleeping easier.